Correct Answer - Option 2 : Rs. 6600

**Given :**

A earns 20% of what B earns. B earns 60% of what C earns and they together earn Rs. 12900 a month.

**Calculations :**

Let the income of A, B and C be A, B and C respectively.

A = 20% of B

A/B = 1/5

B = 60% of C

B/C = 3/5

So

A ; B : C = 3 : 15 : 25 or 3x : 15x : 25x

According to the question

3x + 15x + 25x = 12900

⇒ 43x = 12900

⇒ x = 300

Difference of A and C = 25x - 3x = 22x

⇒ 22 × 300

⇒ 6600 rupees

**∴ Option 2 will be the correct choice.**